Ignition unit for aerosol fire-retarding delivery device

Abstract

An ignition unit for a fire extinguishing assembly has an ignition unit housing with a firing pin disposed within the housing. A spring is coupled to the firing pin, and a restraining device holds the pin in place in the housing. A formed eutectic holds the restraining device in place such that when the eutectic deforms, the firing pin is released and moved by the spring in a desired direction.

The invention claimed is: 
     
       1. An ignition unit for a fire extinguishing assembly, the ignition unit comprising:
 an ignition unit housing; 
 a firing pin disposed within the housing; 
 a spring coupled to the firing pin; 
 a restraining device holding the firing pin in place in the housing; 
 a formed eutectic holding the restraining device in place such that when the eutectic deforms, the firing pin is released and moved by the spring in a desired direction; and 
 a restraining clip positioned to hold the formed eutectic in place. 
 
     
     
       2. The ignition unit of  claim 1  and further comprising a first end that attaches to a fire extinguishing assembly canister such that the firing pin moves toward the canister. 
     
     
       3. The ignition unit of  claim 1  wherein the restraining clip is removable, causing the eutectic to move and the firing pin to move. 
     
     
       4. The ignition unit of  claim 1  wherein the firing pin comprises a groove, and the restraining devices comprises a ball bearing held in the groove by the formed eutectic. 
     
     
       5. The ignition unit of  claim 4  wherein the ball bearing and eutectic are positioned in a passage of the ignition unit transverse to the firing pin. 
     
     
       6. The ignition unit of  claim 5  wherein the groove is angled to leverage the ball bearing outward from the transverse passage. 
     
     
       7. The ignition unit of  claim 1  wherein the spring is in compression against a flange of the inside of the housing while the firing pin is being held in place. 
     
     
       8. The ignition unit of  claim 1  wherein one end of the firing pin is shaped to set off a primer cap when the firing pin is released and moved by the spring. 
     
     
       9. An ignition unit for a fire extinguishing assembly, the ignition unit comprising:
 an ignition unit housing; 
 a firing pin disposed within the housing; 
 means for moving the firing pin; 
 means for preventing movement of the firing pin including a ball bearing and a releasable clip; and 
 means for releasing the firing pin at a predetermined temperature to allow it to be moved by the means for moving the firing pin. 
 
     
     
       10. The ignition unit of  claim 9  wherein the means for releasing the firing pin comprises a formed eutectic. 
     
     
       11. The ignition unit of  claim 9  wherein the formed eutectic deforms at temperatures in the range of approximately 70° C. to approximately 300° C. 
     
     
       12. The ignition unit of  claim 9  and further comprising means for releasably attaching the ignition unit to an aerosol delivery canister. 
     
     
       13. A method of actuating a firing pin to ignite an aerosol based fire extinguisher, the method comprising:
 holding a firing pin under tension in an ignition unit housing with a formed eutectic, the formed eutectic holds a ball bearing against a detent in the firing pin; 
 such that when the formed eutectic reaches a desired temperature, it deforms allowing the ball bearing to move out of the detent, releasing the firing pin such that the firing pin contacts a primer cap, which ignites an ignition mix. 
 
     
     
       14. The method of  claim 13  wherein the formed eutectic deforms at temperatures in the range of approximately 70° C. to approximately 300° C. 
     
     
       15. The method of  claim 13  and further comprising moving the firing pin with a spring. 
     
     
       16. A method of forming an ignition unit for an aerosol based fire extinguisher, the method comprising:
 placing a firing pin having a detent under spring tension; 
 positioning a restraining device against the detent; and 
 positioning a formed eutectic adjacent to the restraining device, the formed eutectic:
 in a first state holds the restraining device in place, and 
 in a second state at a desired temperature the eutectic deforms, the restraining device moves out of the detent, and the firing pin is acted upon by the spring tension. 
 
 
     
     
       17. The method of  claim 16 , wherein the formed eutectic deforms at temperatures in the range of approximately 70° C. to approximately 300° C. 
     
     
       18. The method of  claim 16 , wherein positioning the restraining device against the detent includes positioning a ball bearing against the detent. 
     
     
       19. The method of  claim 16 , wherein positioning the formed eutectic adjacent to the restraining device includes engaging the formed eutectic with the restraining device.